It has long been known that an effective hunting bullet must fulfill a number of conditions.
A. The bullet should be capable of bringing about a fast kill, i.e. produce so much destruction upon the entry of the bullet with near normal strikes in the vicinity of the chest, that the game will not be able to hear or respond to the detonation of the firing. This ensures that the wounded animal will not engage in unnecessary activity or flee, creating problems with subsequent reclamation.
B. The shot should produce a relatively clean entry wound and a sufficiently large but clean exit wound with a significant dispersal of hair, reaching bone parts or blood so that, if the animal escapes, its path may be readily followed.
C. The projectile should maintain a constancy of direction in the body of the animal from the entry point to the exit point so that internal deviation does not occur, even upon traversal of strong bone parts. This minimizes the damage to the game.
D. The projectile should be suitable both for use with large animals and with small animals and thus should be capable of destroying game when used with too small an animal or being capable of killing when used with a larger animal. In other words, the bullets should be versatile with respect to the game against which it is used.
E. The bullet should also have good flight characteristics, i.e. a maximum impact speed for a given initial velocity and range, high accuracy at the usual ranges and good precision (i.e. closeness of targeting with a good weapon).
F. The bullet should, finally, be insensitive to deviations in the flight path produced by normal obstacles and therefor should have a flight path which is substantially unaffected by leaves, grass, reeds, branches and the like.
These requisites are associated with certain mechanical requirements.
This projectile should have a high degree of rotational symmetry, uniformity of mass distribution and good flow dynamics and should have a favorable position of the center of gravity with respect to the point of attack of a projectile upon the body of the animal and against the air.
It should also be capable of being manufactured without special machinery on all conventional machines, should be capable of withstanding the firing gas pressures, barrel friction and air friction, should be free from any tendency to deposit metallic residues in the barrel and should have structural integrity for firing and impact.
I have also been able, after considerable investigation, to determine several parameters which are vital for hunting projectiles if the latter are to be truly efficient for large game.
Firstly, the shock effect is proportional to the product of the tissue resistance R and the projectile speed v in the tissue. P, representing the output of the projectile, can thus be defined by the relation: EQU P = R.sup.. v.
However, since R is a function of the projectile head surface which is, in turn, a function of the product, .pi..sup.. D.sup.2 where D is the diameter of the projectile head. P can be defined as: EQU P = k.sup.. D.sup.2. v,
where k is a constant.
Since v is the entry velocity and is relatively large, D must be small. It has been shown that good results are obtained only if the projectile lags in the animal and mushrooms outwardly relatively slowly.
At the exterior stage of the bullet-penetrating operation, the speed v is assumed to have been reduced appreciably so that D can increase more quickly and the head of the projectile thereby widens more rapidly. Thus, a maximum shock effect and a maximum tearing effect can be obtained.
Reference may also be made to the nerve shock generated around the passage made by the bullet in the animal. The nerve shock is a function of the kinetic energy which is proportional to the mass of the bullet and to the resistance of the body of the animal thereto. If this resistance is not sufficiently great, the bullet leaves the game in a more or less undamaged state and the wounded animal can thereby escape.
It is also important, with hunting bullets to ensure that the exterior wound is of such a nature that it does not close rapidly. For example, if one does not choose to seek escaped wounded game with a bloodhound, it is necessary to follow the trail produced by fluid discharged from the wound. Such discharge will only occur effectively if the exterior wound is substantially larger than the entry wound, this being usually only the same size as the caliber of the bullet. The exterior wound must be several times larger to prevent the skin from blocking the escape of fluids from the exterior wounds.
There is known for so-called humane killings of humans, the use of jacketed pointed military projectiles whose shapes must conform to the Geneva Treaty and are intended to penetrate the body cleanly and leave a small entry and exit wound.
It should be understood, therefore, that systems which utilize jacketed projectiles do not solve the problem dealt with in the present application.
There are, moreover, other situations which require a brief review. Firstly, the projectile must be such that it is capable of penetrating the skin of the animal and carry out this penetration with sufficient energy to allow mushrooming within the animal rather than prior thereto. Premature mushrooming is not desired and indeed it is essential that the projectile be capable of cleanly cutting through the skin at entry. In other words, the projectile must act like a cutter capable of penetrating the skin under the high rotary speed imparted to the projectile by the rifling of the gun barrel.
Secondly, it is desirable that the center of gravity of the projectile shift forwardly rapidly as the projectile passes through the tissues. This forward movement of the center of gravity with respect to, for example, the rear end of the projectile, should take place without eliminating the guiding effect of the cylindrical portion of the bullet. The mushrooming action should not cause the bullet to fall apart and it is desirable that the bullet change in shape or deform without splintering.
Of course, the outer surface of the bullet should be smooth and all edges should be eliminated to minimize the formation of MACH waves or compression waves which dissipate projectile energy to the air.
In view of the foregoing requisites, certain efforts have been made to overcome the disadvantages of the jacketed systems and improve the hunting qualities of a projectile. For example, a so-called "massive projectile", known from the French, has a solid cylindrical guide portion and means for providing a bursting charge at its head, e.g. for whale hunting. However, such projectiles are outlawed for war and are objectionable also as hunting projectiles.
More common, however, is a jacketed bullet in which a lead projectile core is surrounded by a copper or other sheet-metal jacket. The jacket is mushroomed outwardly in flight and occasionally falls apart leaving splinters. The jacket may be of brittle steel which also has a tendency to fall apart and hence the projectile forms a so-called "hail" shot. This has been deemed to be advantageous in hunting since the splinters were believed to increase the shot and damage within the animal.
In practice, however, the increased damage brought about by the formation of splinters is localized at the entry wound and usually the total damage consists of excessive skin damage without significant penetration and therefore with a minimum hunting effect.
It is believed that this disadvantage is a result of the fact that the lead flows over the deformed casing and imparts to the projectile a more or less ball-shape which does not penetrate to any significant effect and which does not cause any material damage after impact.
It has been proposed, therefore, to provide reinforcements on the casing to control the deformation thereof so that the balling up of the lead does not reduce the cutting effect and shock damage of the projectile. However, this has also proved to be unsatisfactory.
In another embodiment of the prior art, jackets of tough tearable material are provided to form long flaps and enable the main body of material in the bullet to mushroom cleanly and to produce a large diameter mushroom-shaped head.
This projectile has been found to be more effective than the first-mentioned one but also has the disadvantage that the opening and mushrooming of the flaps causes the projectile to deform unsymmetrically especially upon penetration of large game.
Another disadvantage is that the bullet may affect small game less and large game more than is required, with significant loss of the meat and damage to the internal structure of the animal.